A gas turbine engine typically includes a fan section and an engine core including a compressor section, a combustor section and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-speed exhaust gas flow. The high-speed exhaust gas flow expands through the turbine section to drive the compressor and the fan section.
Commercial aircraft utilize high-bypass fan sections that generate a proportionally greater amount of thrust then the engine core from the bypass flow. In some high-bypass fan sections a fan variable area nozzle (VAFN or VAN) is installed at an end of the by-pass flow duct and regulate bypass flow by restricting nozzle area. Restriction in bypass flow by the VAN addresses particular conditions encountered during specific operation of the aircraft such as fan flutter during low power descents. Deployment and operation of a VAN involve compromises that provide improved propulsive efficiency and decreased service life. Although a VAN provides some performance benefits, engine designers and manufacturers are continually seeking additional ways to improve performance while also increasing engine service life.